Polyurethane macroinitiator for controlled monomer insertion of styrene

Polyurethane containing alkoxyamine units in the main chain were prepared by polyaddition of diisocyanate with TEMPO-based diol. Radical polymerization of styrene was carried out in bulk with TEMPO-based polyurethane as macroinitiator. GPC, NMR, and IR data revealed that the insertion reaction was accurately controlled to afford the segmented copolymers composed of both urethane groups and polystyrene segments. From the results of model polymerization, it is inferred that the well-defined polystyrene chains were inserted into the macroinitiator. The obtained polymers showed quite different solubility in solvents compared with the macroinitiator and styrene homopolymer. The solubility in polar solvents decreases gradually with increasing inserted polystyrene chain length.